A Foodborne Outbreak Caused by ST8(CC8)-spa t024 Methicillin-Sensitive Staphylococcus aureus Harboring sea, seq, and sek — Taizhou City, Zhejiang Province, China, February 2025

Weiwei Shen^1,&; Xiaoyue Wei^2,&; Haiyan Hu³; Guiwei Zhu³; Ying Sheng¹; Ning Wang¹; Tianlan Pang³; Luwei Wang³; Lingbo Wang⁴; Li Zhan⁴; Zhangnyu Yang⁴; Xiaomei Yan^2,#; Haijiang Lin^1,#

1. Taizhou Center for Disease Control and Prevention (Health Supervision Institute), Taizhou City, Zhejiang Province, China;

2. National Key Laboratory for Intelligent Tracking and Forecasting for Infectious Diseases, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention & Chinese Academy of Preventive Medicine, Beijing, China;

3. Tiantai County Center for Disease Control and Prevention (Health Supervision Institute), Taizhou City, Zhejiang Province, China;

4. Zhejiang Center for Disease Control and Prevention, Hangzhou City, Zhejiang Province, China.

^& Joint first authors.

^# Corresponding author: Xiaomei Yan, yanxiaomei@icdc.cn; Haijiang Lin, linhaijiang@alu.fudan.edu.cn.

This study investigates a foodborne outbreak caused by ST8-spa t024 methicillin-susceptible Staphylococcus aureus (MSSA) in Taizhou City, Zhejiang Province, China, in February 2025. It analyzes the epidemiological characteristics, pathogenic mechanisms, and antimicrobial resistance profiles of the outbreak strains, elucidates their transmission routes, phylogenetic relationships, and the presence of enterotoxin genes and immune evasion mechanisms, providing evidence for public health early warning and prevention. Epidemiological and laboratory investigations involving the isolation of pathogenic microorganisms from food and environmental samples, as well as from patient anal swabs, were conducted. The isolated strains were tested for antimicrobial susceptibility and enterotoxin presence and then subjected to whole-genome sequencing as well as phylogenetic and prophage analyses. Five S. aureus isolates were successfully obtained from seven samples. All isolates belonged to ST8 (CC8)-spa t024, possessed enterotoxin genes (sea, sek, and seq), and exhibited resistance to penicillin. Contaminated rice balls were identified as the source of the outbreak. Phylogenetic analysis helped identify that the outbreak strains of ST8 grouped within a distinct evolutionary Clade II.1 were closely associated with their European lineages. The sea, sek, and seq genes were located on a prophage containing a type D immune evasion cluster, which included the sea, sak, and scn genes. This initial report of an ST8-spa t024 methicillin-susceptible S. aureus food poisoning outbreak in China involved a toxigenic and potentially hypervirulent clone, emphasizing a growing public health concern. It is therefore crucial to strengthen the surveillance of ST8 among food products and handlers.

一起由携带sea、seq和sek基因的ST8(CC8)-spa t024甲氧西林敏感金黄色葡萄球菌引起的食源性疫情 — 台州市，浙江省，中国， 2025年

沈伟伟^1,&，魏销玥^2,&，胡海燕³，朱贵威³，盛莹¹，王宁¹，庞天兰³，王璐韦³，王凌波⁴，占利⁴，杨章女⁴，闫笑梅^2,#，林海江^1,#

1. 台州市疾病预防控制中心（卫生监督所），台州市，浙江省，中国；

2. 传染病溯源预警与智能决策全国重点实验室，传染病预防控制所，中国疾病预防控制中心（中国预防医学科学院），北京，中国；

3. 天台县疾病预防控制中心（卫生监督所），台州市，浙江省，中国；

4. 浙江省疾病预防控制中心，杭州市，浙江省，中国。

^& 共同第一作者。

^# 通信作者：闫笑梅，yanxiaomei@icdc.cn；林海江，linhaijiang@alu.fudan.edu.cn。

本研究针对2025年2月中国台州市ST8-spa t024型甲氧西林敏感金黄色葡萄球菌（MSSA）食物中毒事件，剖析其流行病学特征、致病机制与耐药性谱，阐明传播途径、进化关系及肠毒素基因和免疫逃逸机制，为公共卫生预警与防控提供依据。通过流行病学调查和实验室研究，从食品、环境样本及患者肛拭子中分离致病菌，对分离菌株进行药敏试验和肠毒素检测，并进行全基因组测序及系统发育和前噬菌体分析。从7份样本中分离出5株金黄色葡萄球菌，均为ST8（CC8）-spa t024型，携带肠毒素基因（sea、sek、seq），且对青霉素耐药。污染的饭团被确定为本次爆发的源头。系统发育分析显示，ST8暴发菌株聚类于一个独立的进化分支Ⅱ.1，与欧洲谱系密切相关。sea、sek、seq基因位于一个含D型免疫逃逸基因簇的前噬菌体上，该基因簇包含sea、sak、scn基因。该研究首次报道了中国由ST8-spa t024型甲氧西林敏感的金黄色葡萄球菌引发的食源性暴发事件，涉及一种产毒且可能具有高毒力的克隆株，对公共卫生构成潜在威胁。建议强化对食品及其从业人员中 ST8 型金黄色葡萄球菌的监测力度。

For more information: https://weekly.chinacdc.cn/en/article/doi/10.46234/ccdcw2026.028

Multi-City Outbreak of Staphylococcus aureus Infections Linked to Durian Mille-Feuille Cakes — Shandong Province, China, May–June 2025

Maoqiang Zhuang¹, Xinpeng Li¹, Peirui Xiao¹, Zhengqiao Kong¹, Jian Song¹, Zunhua Chu¹, Liansen Wang^1,#

1. NHC Specialty Laboratory of Food Safety Risk Assessment and Standard Development (Food Microorganisms); Shandong Center for Disease Control and Prevention, Jinan City, Shandong Province, China.

^# Corresponding author: Liansen Wang, wlsen@163.com.

Foodborne diseases peak during summer months due to favorable conditions for pathogen growth, with cold-processed pastries representing high-risk foods susceptible to bacterial contamination. Between May and June 2025, multiple foodborne disease outbreaks occurred across Shandong Province linked to durian mille-feuille cakes from a single franchise brand. Centers for Disease Control and Prevention in three cities (Qingdao, Yantai, and Tai'an) conducted epidemiological investigations from May to June 2025, including case interviews, traceback investigations, and laboratory testing using core genome multilocus sequence typing (cgMLST) for pathogen characterization. Twenty-two confirmed cases were identified across three cities, with a median age of 30 years and 64% female. Laboratory analysis revealed Staphylococcus aureus with enterotoxins A-D to be the pathogen. cgMLST showed clinical isolates, food samples, and food handler isolates differed by only 0-4 alleles in the core gene loci, indicating high genetic relatedness. Food handlers were identified as the likely contamination source rather than raw materials. This multi-city outbreak was caused by durian mille-feuille cakes contaminated by food handlers carrying S. aureus. The franchise business model with decentralized production contributed to the prolonged and geographically dispersed nature of the outbreak. We recommend strengthening hygiene controls throughout the cold-processed pastry production chain, including staff health management, hand hygiene protocols, and temperature control during storage and transport.

一起与榴莲千层蛋糕相关的多城市金黄色葡萄球菌感染暴发事件 — 山东省，中国，2025年5月至6月

庄茂强¹, 李心朋¹, 肖培瑞¹, 孔正桥¹,  宋柬¹, 褚遵华¹, 王连森^1,#

1. 国家卫生健康委食品安全风险评估与标准研制特色实验室（食品微生物领域）；山东省疾病预防控制中心，济南市，山东省，中国；

^# 通信作者：王连森, wlsen@163.com。

2025年5月至6月间，山东省多地发生与某连锁品牌榴莲千层蛋糕相关的暴发事件。省市县三级疾控中心及相关部门进行联合调查以确定致病因素并控制暴发。省市县疾控中心联合开展流行病学调查，包括病例访谈、溯源调查及核心基因组多位点序列分型（cgMLST）以确定病原体。青岛、烟台、泰安三市共确诊22例病例，中位年龄30岁，女性占比64%。实验室确认致病菌为携带肠毒素A、D的金黄色葡萄球菌。cgMLST显示临床、食品及工作人员样本的分离株在核心基因位点仅存在0-4个等位基因差异，表明其具有高度遗传关联性。本次多地市暴发疫情系由携带金黄色葡萄球菌的工作人员污染榴莲千层蛋糕所致。特许经营模式下的分散化生产导致疫情持续时间延长且地理分布广泛。建议加强冷加工糕点生产全链条卫生管控，包括员工健康管理、手部卫生及储运过程中的温度控制。

For more information: https://weekly.chinacdc.cn/en/article/doi/10.46234/ccdcw2026.029

A Local Chikungunya Fever Outbreak Field Investigation — Fujian Province, China, 2025

Shenggen Wu^1,2&, Jiangyi Liu^3&, Zhangbin Tang⁴, Xiaoling Chen³, Yuedong Lin^5,6, Jiawei Lin¹, Ruyi Guo⁷, Weiming Wang^3#, Yuwei Weng^1,2#

1. Fujian Center for Disease Control and Prevention, Fujian Provincial Key Laboratory of Zoonosis Research, Fuzhou City, Fujian Province, China;

2. School of Public Health, Fujian Medical University, Fuzhou City, Fujian Province, China;

3. Quanzhou Center for Disease Control and Prevention, Quanzhou City, Fujian Province, China;

4. Nan'an Center for Disease Control and Prevention, Quanzhou City, Fujian Province, China;

5. Xiamen Center for Disease Control and Prevention, Xiamen City, Fujian Province, China;

6. Chinese Field Epidemiology Training Program, Chinese Center for Disease Control and Prevention & Chinese Academy of Preventive Medicine, Beijing, China;

7. Department of Infectious Diseases, Quanzhou First Hospital Affiliated to Fujian Medical University, Quanzhou City, Fujian Province, China.

^& Joint first authors.

^# Corresponding authors: Yuwei Weng, wengyuwei@fjcdc.com.cn; Weiming Wang, guokeljy@ fjmu.edu.cn.

In late August 2025, a locally transmitted CHIKF outbreak was detected in Licheng District, Quanzhou City, Fujian Province. On September 3, 2025, two locally acquired cases without travel history to Licheng District were reported in the adjacent Nan'an City, Quanzhou City. This study aimed to identify the infection source of the local chikungunya cases in Nan'an City. Field epidemiological investigations were conducted to collect case-related information and trace the infection source.Aedes mosquito density was monitored in the core epidemic area. Whole-genome amplification and sequencing were performed on chikungunya virus (CHIKV)  in the serum samples of the cases. The obtained sequences were aligned with those from GenBank, and a phylogenetic tree was constructed for viral genotypic analysis. Nine days before the onset of the two local cases, an imported chikungunya case from Licheng District had received treatment at Clinic E near their residential area. Whole-genome sequencing revealed complete identity among the CHIKV strains from the two local cases and the one imported case, all belonging to the ECSA genotype. Epidemiological link between the locally acquired CHIKF cases in Nan'an City, Quanzhou and the imported case from Licheng District, Quanzhou. In a previously CHIKV-free non-endemic area with Aedes mosquitoes, secondary local cases may emerge approximately 9 days after the introduction of imported viremic cases.

一起本地基孔肯雅热疫情现场调查 — 福建省，中国，2025年

吴生根^1,2,&，刘江艺^3,&，汤章彬⁴，陈晓玲³，林越东^5,6，林嘉威¹，郭如意⁷，王伟明^3,#，翁玉伟^1,2,#

1. 福建省疾病预防控制中心，福建省人兽共患病研究重点实验室，福州市，福建省，中国；

2. 福建医科大学公共卫生学院，福州市，福建省，中国；

3. 泉州市疾病预防控制中心，泉州市，福建省，中国；

4. 南安市疾病预防控制中心，泉州市，福建省，中国；

5. 厦门市疾病预防控制中心，厦门市，福建省，中国；

6.中国现场流行病学培训项目，中国疾病预防控制中心（中国预防医学科学院），北京，中国；

7. 福建医科大学附属泉州第一医院感染病科，泉州市，福建省，中国。

^& 共同第一作者。

^# 通信作者：翁玉伟，wengyuwei@fjcdc.com.cn；王伟明，guokeljy@fjmu.edu.cn。

2025年8月下旬福建省泉州市鲤城区出现本地基孔肯雅热疫情，9月3日相邻泉州市南安市报告2例无鲤城旅居史的本地病例。本研究旨在明确南安市本地病例感染来源。开展现场流调，收集病例相关信息，追溯感染源；在核心区监测伊蚊密度，对病例血清基孔肯雅热病毒进行全基因组扩增测序，结合GenBank序列进行比对，构建系统发育树分析基因型。2例为南安市首次报告的本地确诊基孔肯雅热病例，3名共同暴露者无症状且检测阴性。患者发病前9天其居住地附近的E诊所曾治疗过1例鲤城区输入病例，3例（2例本地+1例输入）病例病毒全基因组序列完全相同，属ECSA基因型。南安市本地病例与鲤城区输入病例存在关联。无基孔肯雅热病毒但有伊蚊的非流行区，输入病毒血症病例后约9天即可出现本地续发病例。

For more information: https://weekly.chinacdc.cn/en/article/doi/10.46234/ccdcw2026.030

First Human Case of Streptococcus parasuis Infection — Henan Province, China, 2025

Pengyun Zhang^1,2; Shuangling Li^1,2; Xue Luo³; Yafei Li³; Xiaolong Ma^1,2; Hui Li^1,2; Xin Zhu^1,2,#; Yinxia Zhu^1,2

1. Luoyang Key Laboratory for The Etiology of Vector-borne Diseases; Luoyang Center for Disease Control and Prevention, Luoyang City, Henan Province, China;

2. Henan Provincial Center for Disease Control and Prevention, Zhengzhou City, Henan Province, China.

^# Corresponding authors: Xin Zhu, luoyang-zhuxin@163.com.

On June 26, 2025, a hospital in Luoyang city reported a suspected case of Streptococcus suis infection. The local CDCs immediately initiated an epidemiological investigation upon notification. Blood samples were collected from the patient for microbial culture. The isolated strain HN04 underwent species identification and phylogenetic analysis through matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), real-time quantitative polymerase chain reaction (qPCR) targeting Streptococcus suis-specific nucleic acid sequences, and whole-genome sequencing. MALDI-TOF MS initially identified strain HN04 as Streptococcus suis; however, the S. suis-specific qPCR assay produced a negative result. Average nucleotide identity (ANI) analysis definitively identified HN04 as Streptococcus parasuis. Phylogenetic analysis revealed that HN04 was distantly related to previously reported clinical isolates from China. Epidemiological investigation found no documented history of livestock contact, particularly with pigs, suggesting environmental exposure as the likely transmission route. This study documents the first confirmed human case of Streptococcus parasuis infection in Henan Province, suggesting widespread environmental distribution of this pathogen and highlighting the need for surveillance beyond occupational risk groups. We recommend including S. parasuis in the differential diagnosis for patients presenting with severe traumatic infections even in the absence of livestock contact history. Enhanced environmental surveillance systems and rapid diagnostic capabilities are urgently needed. These findings provide critical insights into the epidemiological characteristics and transmission dynamics of S. parasuis.

首例人感染副猪链球病例 — 河南省，中国，2025年

张鹏云^1,2；李双玲^1,2；罗雪³；李亚飞³；麻小龙^1,2；李会^1,2；朱鑫^1,2,#；朱银霞^1,2

1. 洛阳市媒介传染病病原学重点实验室，洛阳市疾病预防控制中心，洛阳市，河南省，中国；

2. 河南省疾病预防控制中心，洛阳市，河南省，中国。

^& 共同第一作者。

^# 通信作者：朱鑫, luoyang-zhuxin@163.com。

对河南省首例人感染副猪链球病例开展流行病学调查，探索感染来源，为副猪链球菌的流行病学特征与传播风险研究提供重要参考。采集患者的血液样本进行微生物培养，通过质谱鉴定、实时荧光定量PCR（qPCR）检测、全基因组测序对菌株HN04进行种属鉴定和系统发育分析。菌株HN04质谱鉴定结果为猪链球菌，猪链球菌qPCR检测结果为阴性。通过计算平均核苷酸一致性（ANI），准确地将HN04鉴定为副猪链球菌。系统发育分析表明，HN04与我国以往的病例分离株亲缘关系较远。流行病学调查显示，病例无明确的猪等家畜接触史，提示可能因环境暴露而感染。本研究报道河南省首例人感染副猪链球菌病例，提示该菌可能在环境中广泛存在，防控工作需突破职业人群。建议将其纳入无明确家畜接触史的严重创伤感染患者的鉴别诊断，并加强环境监测与快速检测能力。

For more information: https://weekly.chinacdc.cn/en/article/doi/10.46234/ccdcw2026.031